This invention relates to metal crystallites disposed in a carbonaceous material matrix and more particularly to metal crystallites disposed in a carbonaceous matrix prepared by growing microbes in a metal ion or metal ion complex rich environment, harvesting said microbes containing said metal and pyrolizing.
In applications such as elecrodes for chlorine/alkali cells, batteries and fuel cells, it is often desirable to utilize high surface area platinum powder supported on carbon as part of the electrode active layer. In the past, these types of applications used platinum crystallites in the 20 angstrom size region on a carbon support but were only metastable due to the sinterng processes necessary to make these types of materials.
Other metal crystallites have also been found to be beneficial because of their large surface area for other types of electrodes in addition to the platinum carbon electrodes described hereinabove.
In a related area, it is known to remove metal contaminants from a process waste stream by using absorption into living organisms, namely plants, as is described, for example, in Water Purification and Waste Water Treatment Disposal, Fair, Geyer and Okun, John Wiley & Sons, 1968; Elements of Water Supply and Waste Water Disposal, second edition, Fair, Geyer and Okun, 1971; and Water-1976 II Biological Waste Water Treatment, Bennett editor, 167 volume 73, 1977. However, all of these technologies dealing with absorbing the metal in process waste streams do not deal with the recovery and utilization as high dispersion metal crystallites supported in a carbonaceous material matrix. Thus, they do not move forward to the point where applicants' present invention lies.
East German Pat. No. 95,313 issued Jan. 20, 1973, to Horst Steppan describes a method of using a microorganism to deposit a metal on an object by biological-fermentation (i.e., by biologic oxidation and reduction). The metallization is done on the container walls and/or on an object suspended in the fermentation bath. There is no teaching or even speculation on how to provide metallic particles homogeneously suspended in a carbonaceous material matrix while preventing oxidation of the metal ions.
Likewise, the recovery of precious metals out of process waste streams via incorporation into living organisms and then pyrolizing to provide metallic precious metal dispersed in a carbonaceous material has not previously been described in the art. Generally these recoveries have been done via electrowinning such as taught, for example, in U.S. Pat. Nos. 4,095,975 and 4,033,765. Alternatively cation exchange resins have been used to recover these precious metals in process waste streams.